Method for the production of pigmented rayon



y 27, 1952 R. A. MORSE 2,598,066

METHOD FOR THE PRODUCTION OF PIGMENTED RAYON Filed NOV. 7, 194'? HIGH PRESS URE VHCUUM VACUUM HIGH PRESSURE HIGH PRESS U25 .2? INVENTOR.

Patented May 27, 1952 .METHOJD FQRJIHE L PRODUCTION OF ,"P GMENTEDI'K TYON "'Applioation'November 7, 51947; Serial "N02" 78 1521 -The R present invention relates to an" improved emethod ion-manufacturing cast=-and-extruded products such as rayon or the like and itrelates more particularly to an improved-method tr -..producing- 'delusteredorpigmentedrayon.

In the manufacture of dull or pigmented rayon, according to methods-now generally employed, a "spigment or a-delustering agent, preferably of higharefractive index, is dispersed --in extremely powdered-form in the spinningsolution.

*r This-is almost universally accomplished-by forming an aqueous creamIi-ke slurry of the powdered 'd'elustering agent. 1 For example; finely powdered -titanium dioxide, ahighly satisfactoryidelustering agent, is -mixed with a weak' alkalinesolution -and-..treated-in= a' ball mill' for several hours. 111 '-'order to insure a stable and'un'i-form dispersion -of the titanium dioxide 7 in the; slurry: it=is neces- {sary to employ titanium dioxide of predetermined ssurface characteristics and-to maintain theslurry at? a predetermined: pH. Moreover the surface electrical cha-racteristic ofitheballmill may otten :inh-ibit the desired dispersing of. the :titanium'flioxide thus rendering the i equipment inadequate.

'The titanium dioxideslurry-is then introduced as abatch into abatch of the spinningsolution, f-for examplewiscose, and-the vmixture ris -con- 'zztinuously stirred. The mixing of {the titanium dioxide slurry and theviscose is performed in the a tank containing: the viscose which is either :ready or being prepared for spinning. In the mormal arayon installation which generally.includesmany espinning machines it is necessary- -to: spin either ypigmented, "dull or bright yarn throughout: *Ithe --installation: to the total-- exclusion :of the=wother etypesof yarn.

'Ihe: drawbacks of the methods-heretofore=employed in I the: production: of delustei ed win-pigamented rayon yarn-i are -numerous.and-:iobvious.

The-@time-- consu-med is great, and themethods slack:--versatility. :They require very close ;;and rigid-process control; any. wide deviation resulting ".inapoor product often unsuitedifor'thezpurpose *tdesired; because of: the resultingnoneuni-formity wand; poorwquality 1 of the product. #Moreover; -in;

-:-most; casesrit -is1notr-practica-lly feasible-toaemploy irthesewmethodsiii-part ofarayon: installation awhile;,thelremainder, of; theinstal-lation-is engaged in the manufacture of a lustrous product. tilt; is

xther foran :obiect of:;th present-d nti n o .rovide animprovedz;method;jor:;the;=:manufac -n ide usteredaorrpi mented-rayo -znrox d za rimpmvedxmethod;ion

rformly an wd edip g ent.eridel i tennaraeen (Gl-.-}106+:i1:66)

=such as: titaniumd-ioxide, ina rayon spinning solution. Y

Still another-obj ect of the-presentinvention' is te-provide an improvedmethod for the produc- 5 tion-ofpigmenteddelustered-rayonby the viscose methodcharacterized by the flexibility. and-- ease of'application.

, A further object of -the= present invention is to provide an im-proved method for thepmduc- 10 tion of pigmented or delustered-=rayonwwherein any desired '-number -of spinning -uni-ts-maw be aselectively -adj-ustedto spin eitherebright dull or: pigmented rayon without anyinterrupti-on -in the operation of the individual spinning units. I l Still a further -=ob ect of the presentinvention =-isitoprovide an improved-=method for the pro- :d-uction of pigmen-ted: or =delustered rayom which method may be-easily applied to: existing rayon producing installations-awithoutwany appreciable interference in= the continued outputofithe installation.

The a-bo-ve;andotheriabjeots of tlie presentinvention;vwill becomeapparent irom-,a -reading of the-following descriptiontaken with the accomzypan'ying drawing, :which diagrama-tically oil-lustrates a-- pref erred embodiment of theipresent invention.

The present invention contemplates forminga 1 stableslurry of: a pigment or delustering agent,

gg alldinjecting the slurry in-metered amountswinto the-spinning solution during :its :travelttrom-rthe spinning solution tank to the spinnerettesioitexi trudingdevices. The=rateof=injection otithapigment or delustering agent :slurry in'tOithBfSpin- 1: 5-= ningasolutiongis controlledwby:theisflow -1of; the

spinning solutioni to -the' spinningunits.

Anothernfeatureof the present inventiom-comprises 1 the :improved method of formingta: stable slurry of a pigment or delusteringeagenw:such :as ,titanium dioxide wherein ithmpowdere pig- --ment-oridelustering agentv isrfirst uniformlyedis- -persed -in.an amount of spinning zsolutionttozproduce a massofeveryzstiffz :dough-like consistency, :in which the'pigment. or .deluster-ingagentis-uni- 5 formly dispersed. Q This -mass of. stiiiadgughelike --consistency :is then:gradually-. dilutedzto; a point where it may be -readilwmi-xed in' the spinning ----solution.

-=More--specifically;thefinelypowderedpigment Y ordelusteringaagent, for example titaniumtdioxideg: is;uniformlyi dispersedt by means; ofaany titanium dioxide and 25% viscose. ,.noted that the relative proportions of the pigbeing kneaded by the dispersing mechanism, until the mass assumes an easily metered and flowing consistency of predetermined proportions of viscose and titanium dioxide. The resulting slurry is then suitably filtered and deaerated and injected into the spinning solution on its way from the spinning solution tank to the extruding devices. The rate of injection of the slurry into the spinning solution is controlled by the rate of flow of the spinning solution, so that the proportion of titanium dioxide to spinning solution is constant and independent of the rate of how of the spinning solution. The spinning solution and the injected titanium dioxide are subjected to a mixing operation prior to the extrusion of the spinning solution.

Reference is now made to drawing wherein i designates a dispersing type of kneader of any well-known design, which communicates by way of conduits 2 and a relatively slow metering device 3 to a source of spinning solution, for example, viscose. The outlet of the kneader -i is connected through a valve 4 to a tank 5;

which tank 5 communicates through the valve 6 to a source of high pressure air. Further, the tank 5 is connected to an'inlet of a suitable filter press 1' the outlet of which is connected through valves 8 and 9 to the tanks l0 and I i respectively. Moreover, each of the tanks, l0 and H, may be selectively connected through corresponding valves l2 and I3 to a source of air under pressure, or to an evacuating pump. The outlets of the tanks ID and H are connected through valves l4 and respectively to the inlet of a suitable metering device IT, which may be a gear pump or any other desired type. A second and relatively larger metering device l8, which may likewise be of a gear pump or similar type, has its inlet connected to a main reservoir [9, containing a solution ready for spinning, the spinning solution being under pressure. The metering device I8 is driven by a low power electric motor 26, which has its drive shaft connected through an adjustable speed reduction unit 2! to the drive shaft of the metering device 11. The outlet of the metering device I8 is connected through a conduit 22 having an enlarged portion 23 to the spinning units, not shown, each of which may 'consist of a multiplicity of spinning machines or spinnerettes immersed in a suitable setting bath.

Further, the outlet of the metering device 11, is connected through a conduit 24 and through a jet 25, to the conduit 22 posterior to the enlarged portion 23 of the conduit 22. A paddle or other stirring member 26, is disposed within the enlarged portion 23 and is driven by an electric motor 27.

Considering now the present improved process and the operation of the apparatus above described and illustrated in the accompanying drawing, a predetermined amount of spinning solution, for example, viscose and a predetermined amount of powdered pigment or delustering agent, for example, titanium dioxide, are deposited in the kneader I, the proportions being between approximately 65% and 85% titanium dioxide and 65% and viscose preferably between 73% and 80% titanium dioxide and 20% and 27% viscose, for example 75% It should be ment or delustering agent and the spinning sothe pigment or delustering agent and the spinning solution employed. The kneader is driven for a period of a few minutes, until the titanium dioxide is uniformly dispersed in the viscose and the mixture becomes a very stiff dough-like mass. Thereafter, the metering device 3 is actuated, slowly introducing an additional predetermined amount of viscose into the kneader l, which continues in its operation.

When the dough-like mass has been transformed into a uniform flowable slurry, preferably not containing an excess of 50% titanium dioxide, for example 25% titanium dioxide and viscose, the valve 4 is opened, and when the slurry has completely drained from the kneader l into the tank 5, valve 4 is closed and the valve 6 is opened, admitting compressed air into the tank 5, which urges the slurry through the filter press I and into one of the tanks II! or II, depending upon which of the valves, 8 or 9, is open. Upon the slurry being completely filtered and being disposed in, for example tank [0, the valves 8 and 14 being closed, the valve 12 is adjusted so as to connect the interior of the tank 10 to a vacuum source where the slurry is exposed for a time sufdcient to substantially deaerate the same.

After the slurry in tank I0 has been deaerated, the valve I2 is switched, so that the tank It! is connected to a source of high pressure air. The valve I4 is then opened, thereby introducing the slurry into the metering device H, which accurately meters the slurry into the spinning solution. More particularly the spinning solution from the reservoir l9 and the slurry from the tank 10 are respectively metered by the metering devices l8 and H,- which are cooperatively driven by the motor 20 and the speed reduction unit 2|. The relative proportions of the slurry and the spinning solution may be suitably adjusted by means of the variable ratio speed reduction unitv 2|, thereby controlling the degree of delustering. Furthermore, the pressure on the spinning solution in the reservoir i9 and the slurry in the reservoir I0, is just short of sufficient to pass through the metering devices 18 and I! of the gear pump type, so that the low power electric motor 20 is all that is necessary to drive the metering devices I8 and I1. Moreover, the speed of the metering device i8 and hence of the metering device I! is controlled by the rate of flow of the spinning solution, which in turn is controlled by the consumption of spinning solution by the spinning units. The slurry and the spinning solution are mixed at the point where the slurry nozzle 25 enters the conduit 22, and the slurry is then uniformly dispersed in the spinning solution in the enlarged portion of the conduit by means of the stirrer 26. The spinning solution containing the pigment or delustering agent is then spun, extruded or cast in any well-known manner. It should be noted that while one of the tanks I0 or H contains the slurry dispersed pigment or delustering agent which is being injected by way of the metering device I'I into the spinning solution, the other of the tanks ll! or II is being deaerated, so that the slurry may be continuously available.

An important advantage gained by employing the present method of mixing a pigment or delustering agent with the spinning solution, is that the concentration of the pigment or delustering agent in the spinning solution is independent -of the rate of flow of the spinning solution. Another advantage is that any number of spinning units may be employed or may be discontinued at will, without interfering with the optimum operation of the other spinning units. A further advantage gained by the present process of forming a slurry is that the time consumed in making the slurr is a few minutes, as compared with several hours where other methods are employed. Moreover, the degree of process control required is small, as it has been earlier pointed out, and the number of operations has been reduced.

While there has been described and illustrated a preferred embodiment of the present invention, it is obvious that numerous alterations and omissions may be made without departing from the spirit thereof.

I claim:

1. Method of producing a pigmented extruded cellulosic product comprising uniformly dispersing by kneading a predetermined amount of a powdered pigment in a predetermined amount of viscose spinning solution to form a mass of stiff dough-like consistency, diluting said mass while kneading with additional viscose spinning solution to produce a flowable slurry of said pigment in said viscose and continuously injecting said slurry into a flowing viscose spinning solution to produce a spinning solution having. uniformly dispersed therein said pigment at the desired concentration.

2. The method of producing delustered rayon, comprising uniformly dispersing a predetermined amount of a powdered delustering agent in a predetermined amount of viscose spinning solution to produce a mass of dough-like consistency, adding a further predetermined amount of viscose spinning solution to said dough-like mass while kneading the same to produce a slurry, and introducing said slurry into a viscose spinning solution in predetermined proportions prior to the spinning thereof.

3. The method of producing delustered rayon by the viscose method comprising uniformly dispersing finely powdered titanium dioxide in viscose to form a dough-like mass, slowly adding additional viscose to said mass while kneading the same to produce a uniform slurry of titanium dioxide of heavy cream-like consistency, deaerating said slurry, injecting said slurry into deaerated viscose in a condition for spinning at a rate controlled by the rate of flow of the viscose to the spinning system, and continuously and uniformly dispersing the titanium dioxide in said slurry in said viscose spinning solution.

4. The method of producing delustered viscose type rayon comprising the steps of mixing between and titanium dioxide and between 15% and 35% viscose, kneading said mixture until a plastic doughlike mass is produced having the titanium dioxide uniformly dispersed in the viscose, thereafter adding to said mixture while continuing said kneading operation additional viscose until a uniform flowable slurry results containing not in excess of 50% titanium dioxide and introducing said slurry into a viscose spinning solution at a predetermined rate prior to the spinning thereof to produce a spinning solution having uniformly dispersed therein said titanium dioxide at the desired concentration.

REGINALD A. MORSE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,895,192 Kampf Jan. 24, 1933 1,938,312 Bassett et al Dec. 5, 1933 1,955,825 Palmer Apr. 24, 1934 2,000,003 Verbyla Apr. 30, 1935 2,039,708 Crouch May 5, 1936 2,324,567 Dreyfus et al July 20, 1943 

1. METHOD OF PRODUCING A PIGMENTED EXTRUDED CELLULOSIC PRODUCT COMPRISING UNIFORMLY DISPERSING BY KNEADING A PREDETERMINED AMOUNT OF A POWDERED PIGMENT IN A PREDETERMINED AMOUNT OF VISCOSE SPINNING SOLUTIONTO FORM A MASS OF STIFF DOUGH-LIKE CONSISTENCY, DILUTING SAID MASS WHILE KNEADING WITH ADDITIONAL VISCOSE SPINNING SOLUTION TO PRODUCE A FLOWABLE SLURRY OF SAID PIGMENT IN SAID VISCOSE AND CONTINUOUSLY INJECTING SAID SLURRY INTO A FLOWING VISCOSE SPINNING SOLUTION TO PRODUCE A SPINNING SOLUTION HAVING UNIFORMLY DISPERSED THEREIN SAID PIGMENT AT THE DESIRED CONCENTRATION. 